By the end of the 1980s only two microtubule-dependent motors, the plus end-directed kinesin and the minus end-directed cytoplasmic dynein, had been identified. At the time, these two motors seemed almost sufficient to explain directional motility events on polar microtubule tracks in the cell. No- theless, shortly after, the tip of the iceberg began to emerge with the identi- cation of proteins containing in their sequences a domain found in kinesin. This domain, called the motor domain, conferred on these proteins the essential property of moving on microtubules, using the energy derived...

By the end of the 1980s only two microtubule-dependent motors, the plus end-directed kinesin and the minus end-directed cytoplasmic dynein, had been identified. At the time, these two motors seemed almost sufficient to explain directional motility events on polar microtubule tracks in the cell. No- theless, shortly after, the tip of the iceberg began to emerge with the identi- cation of proteins containing in their sequences a domain found in kinesin. This domain, called the motor domain, conferred on these proteins the essential property of moving on microtubules, using the energy derived...